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1.
Gastrointest Endosc ; 99(2): 193-203.e5, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-37709151

RESUMO

BACKGROUND AND AIMS: We compared ERCP using a balloon-assisted endoscope (BE-ERCP) with EUS-guided antegrade treatment (EUS-AG) for removal of common bile duct (CBD) stones in patients with Roux-en-Y (R-Y) gastrectomy. METHODS: Consecutive patients who had previous R-Y gastrectomy undergoing BE-ERCP or EUS-AG for CBD stones in 16 centers were retrospectively analyzed. RESULTS: BE-ERCP and EUS-AG were performed in 588 and 59 patients, respectively. Baseline characteristics were similar, except for CBD diameter and angle. The technical success rate was 83.7% versus 83.1% (P = .956), complete stone removal rate was 78.1% versus 67.8% (P = .102), and early adverse event rate was 10.2% versus 18.6% (P = .076) in BE-ERCP and EUS-AG, respectively. The mean number of endoscopic sessions was smaller in BE-ERCP (1.5 ± .8 vs 1.9 ± 1.0 sessions, P = .01), whereas the median total treatment time was longer (90 vs 61.5 minutes, P = .001). Among patients with biliary access, the complete stone removal rate was significantly higher in BE-ERCP (93.3% vs 81.6%, P = .009). Negative predictive factors were CBD diameter ≥15 mm (odds ratio [OR], .41) and an angle of CBD <90 degrees (OR, .39) in BE-ERCP and a stone size ≥10 mm (OR, .07) and an angle of CBD <90 degrees (OR, .07) in EUS-AG. The 1-year recurrence rate was 8.3% in both groups. CONCLUSIONS: Effectiveness and safety of BE-ERCP and EUS-AG were comparable in CBD stone removal for patients after R-Y gastrectomy, but complete stone removal after technical success was superior in BE-ERCP.


Assuntos
Colangiopancreatografia Retrógrada Endoscópica , Cálculos Biliares , Humanos , Colangiopancreatografia Retrógrada Endoscópica/efeitos adversos , Estudos Retrospectivos , Cálculos Biliares/diagnóstico por imagem , Cálculos Biliares/cirurgia , Gastrectomia , Ducto Colédoco , Endoscópios , Resultado do Tratamento
2.
Healthcare (Basel) ; 11(20)2023 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-37893843

RESUMO

[Aim and Background] People's lifestyles changed considerably due to the coronavirus disease 2019 (COVID-19) pandemic. The number of patients with acute pancreatitis (AP) can be expected to decrease as alcohol consumption decreases. This study was conducted to assess COVID-19 pandemic effects on AP patients in a Japanese regional hospital. [Methods] Based on the first and second states of emergency declarations in Tochigi Prefecture, the survey periods were set as follows: period A, 16 April-14 May; period B, 15 May-13 January; period C, 14 January-7 February; and period D, 8 February-15 April. Using data acquired in 2017, 2018, 2019, and 2020, we retrospectively reviewed the number of patients admitted to our hospital with a diagnosis of AP, and their clinical characteristics. [Results] According to a National Tax Agency survey, the average alcohol sales per adult in Tochigi Prefecture were 71.3 L in 2017 before the pandemic, and 64.0 L in 2021 under the pandemic. The number of AP patients in 2020 was 38% lower than in 2017. Comparing 2017 with 2020, the number of alcoholic AP patients was lower in 2020 (p = 0.007). [Conclusions] The findings suggest that COVID-19-pandemic-related lifestyle changes contributed to the decrease in AP patients.

3.
J Clin Med ; 12(16)2023 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-37629362

RESUMO

[Background and study aim] A commonly applied method for diagnosing chronic pancreatitis (CP) uses endoscopic ultrasonography (EUS), assigning weights to each EUS diagnostic finding. It is the Rosemont classification (RC). In 2019, to improve EUS diagnostic specificity, Japanese diagnostic criteria for early chronic pancreatitis (ECP) were revised. Nevertheless, the criteria use no weighting of EUS diagnostic findings, as the RC does. This study was undertaken to propose diagnostic criteria that would weight each EUS finding of ECP and that would be more specific than the RC. [Methods] By EUS of the pancreas, 773 patients underwent detailed observation from January 2018 to March 2019 at our institution. An expert finalized all cases when patients were diagnosed. Using data from the medical records, 97 consecutive patients with EUS diagnostic findings of ECP based on the Japanese diagnostic criteria of ECP2009 (JDCECP2009) were selected. The definition under the RC of "Indeterminate for CP" was equivalent to ECP. Each case was diagnosed using (1) JDCECP2009 and (2) the Japanese diagnostic criteria of ECP2019 (JDCECP2019). Moreover, the four diagnostic EUS findings in JDCECP2019 were applied to the RC, weighted (modified-JDCECP2019), and subsequently compared with the earlier diagnostic criteria. As Modified-JDCECP2019, we suggested (3) RC-A-the current four items scored related to the RC, and (4) RC-B-the five items scored by dividing lobularity with and without honeycombing. [Results] Diagnoses produced based on each criterion were normal: ECP = (1) 20:77, (2) 46:51, (3) 52:42, and (4) 60:35. [Conclusions] Modified-JDCECP2019 may provide EUS diagnoses for ECP with higher specificity.

4.
DEN Open ; 3(1): e220, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-37009517

RESUMO

A woman in her 60s underwent endoscopic sphincterotomy for choledocholithiasis. Unfortunately, post-endoscopic retrograde cholangiopancreatography pancreatitis occurred. In addition, huge walled-off necrosis (WON) appeared as a late complication. For the infected WON, endoscopic ultrasound-guided fistuloplasty and endoscopic necrosectomy were performed, and a double pigtail plastic stent (PS) (7Fr, 7 cm) was placed to prevent a recurrence. Plain computed tomography conducted two years later showed that the stent implanted for WON had deviated. The distal end of the stent was found to have migrated into the bile duct. In addition, common bile duct stones with stents as nuclei were observed. Upon performing endoscopic retrograde cholangiography, it was revealed that the stent tip perforated the distal bile duct just above the papilla. After removal of the stent using grasping forceps, we made an incision between the duodenal - bile duct fistula and bile duct orifice using a sphincterotome. Then, the stone was removed by a balloon catheter. Although such late adverse events are rare occurrences, placement of long-term PS after treatment of WON should be followed up regularly with imaging examination, and if there is no recurrence for several months, removal of the PS at that point may be considered.

5.
DEN Open ; 3(1): e164, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-36176351

RESUMO

Endoscopic ultrasound (EUS) is widely recognized for its non-invasiveness and for its usefulness in chronic pancreatitis (CP) diagnosis, including early CP. Although it is desirable to obtain a definitive diagnosis of CP by tissue sampling with EUS-guided fine needle aspiration, histopathological changes in CP are heterogeneous in terms of the extent and the distribution of lesions. Therefore, histopathological diagnosis of appropriate tissue sampling by EUS-fine needle aspiration is expected to be difficult. Furthermore, it is virtually impossible to match EUS images with pathological sections, making direct contrast between EUS findings and pathology difficult. This narrative review presents a discussion of the diagnosis of CP/early CP by EUS, particularly assessing the association between ultrasound and pathological findings. Recently, the histological corroboration and correlation of EUS findings related to CP have been clarified by surgical specimens, including those obtained from animal studies. Furthermore, remarkable advances have occurred in the objective and quantitative diagnosis of pancreatic fibrosis by EUS-elastography. Future technological advances in EUS are expected to improve the accuracy of diagnosis of pancreatic fibrosis at earlier stages.

6.
J Clin Med ; 11(20)2022 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-36294419

RESUMO

Background: Endoscopic ultrasound-guided puncture aspiration biopsy (EUS-FNA) of pancreatic ductal adenocarcinoma (PDAC) is highly diagnostic, but it is difficult to distinguish from benign disease. Our objective was to determine the usefulness of maspin staining, in addition to conventional p53 staining, in the diagnosis of PDAC by EUS-FNA. Methods: Of the patients who underwent EUS-FNA and were diagnosed with PDAC, we retrospectively identified 90 cases in which both maspin and p53 staining were performed. In addition, we identified 28 cases of benign pancreatic disease diagnosed using EUS-FNA and these were selected as a control group. For analysis of EUS-FNA specimens, Cohen's Kappa (κ) coefficient and the prevalence and bias adjusted Kappa statistic (PABAK) were applied to assess the significance of sensitivity and specificity, comparing p53, maspin, p53+maspin. Results: The sensitivity and specificity of p53 staining were 48.9% and 100%. The κ coefficient was 0.31 (95%CI 0.18−0.44) (p < 0.01) and the PABAK coefficient was 0.22 (95%CI 0.03−0.40). The results for maspin staining were 88.9% and 92.9%. The κ coefficient was 0.72 (95%CI 0.54−0.90) (p < 0.01) and the PABAK coefficient was 0.78 (95%CI 0.64−0.88). The results for the combination of maspin and p53 staining were 94.4% and 92.2%. The κ coefficient was 0.82 (95%CI 0.64−1.00) (p < 0.01) and the PABAK coefficient was 0.86 (95%CI 0.74−0.94). Conclusion: Adding maspin staining to p53 staining showed high sensitivity and specificity. Our results demonstrated the usefulness of their combined use that might contribute to the improvement of tissue diagnostic performance of PDAC by EUS-FNA.

7.
Healthcare (Basel) ; 10(7)2022 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-35885720

RESUMO

Red color sign-positive (RC-positive) esophageal varices present a high bleeding risk, necessitating prophylactic treatment. Among RC-positive esophageal varices, those classified morphologically as small straight varices (Form level 1: F1) are difficult to treat. Moreover, the appropriate time for therapeutic intervention remains undefined. This study assessed the bleeding risk in RC-positive F1 esophageal varices. After extracting 541 cases of F1 esophageal varices diagnosed during 1 January 2012−29 February 2020, 76 cases of RC-positive F1 esophageal varices were divided into two groups in terms of treatment intervention at diagnosis: 49 cases with (treatment group) and 27 cases without (follow-up group). We assessed the bleeding rates, bleeding-associated factors, and early-bleeding-associated factors. The treatment group's bleeding rate was 10% (5/49). The follow-up group's bleeding rate was 78% (21/24). The subsequent bleeding rate was low in the treatment group (p < 0.001). The median period of sustained absence of bleeding was longer in the treatment group than in the follow-up group (1156 [274−1582] days vs. 105 [1−336] days; p < 0.001). In the follow-up group, a significant number of bleedings had varices that included a hematocystic spot (HCS) as RC or combined with RC (p = 0.017). Early bleeding occurred often in varices that included HCS or combined with RC (p = 0.024). Red wale marking (RWM) only was not a factor of early bleeding (p = 0.012). In conclusion, RC-positive varices should be treated even as F1 varices. Patients with RWM only show the possibility of not accepting early treatment intervention. A fast response is crucially important in HCS cases because of its associated bleeding and early bleeding.

8.
World J Gastroenterol ; 28(5): 594-601, 2022 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-35316958

RESUMO

BACKGROUND: Adult-onset Ménétrier's disease is strongly associated with Helicobacter pylori (H. pylori) infection and an elevated risk of carcinogenesis. Cases of early-stage gastric cancer developed in H. pylori-negative Ménétrier's disease are extremely rare. We report a case of early gastric cancer in H. pylori-negative Ménétrier's disease that was curatively resected with endoscopic submucosal dissection (ESD). CASE SUMMARY: A 60-year-old woman was referred to our hospital after her medical examination detected anemia. Contrast-enhanced upper gastrointestinal (UGI) radiography revealed translucency of the nodule-aggregating surface with giant rugae. Blood tests showed hypoproteinemia and were negative for serum H. pylori immunoglobulin G antibodies. The 99mTc-DTPA-human serum albumin scintigraphy showed protein loss from the stomach. UGI endoscopy showed a 40-mm protruding erythematous lesion on giant rugae of the greater curvature of lower gastric body, suggesting early-stage gastric cancer due to Ménétrier's disease. En bloc resection with ESD was performed for diagnosis and treatment. Histology of ESD showed well-differentiated tubular adenocarcinoma. The cancer was confined to the mucosa, and complete curative resection was achieved. Foveolar hyperplasia and atrophy of the gastric glands were observed in non-tumor areas, histologically corresponding to Ménétrier's disease. Three years after ESD, gastric cancer had not recurred, and Ménétrier's disease remained in remission with spontaneous regression of giant gastric rugae. CONCLUSION: Complete curative resection was achieved through ESD in a patient with early-stage gastric cancer and H. pylori-negative Ménétrier's disease.


Assuntos
Ressecção Endoscópica de Mucosa , Gastrite Hipertrófica , Helicobacter pylori , Neoplasias Gástricas , Adulto , Feminino , Gastrite Hipertrófica/diagnóstico , Gastrite Hipertrófica/diagnóstico por imagem , Gastroscopia , Humanos , Pessoa de Meia-Idade , Recidiva Local de Neoplasia , Neoplasias Gástricas/patologia
9.
Dig Endosc ; 34(6): 1214-1221, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35108413

RESUMO

OBJECTIVES: Ultrasound speed (USS) correction improves image quality by estimating the optimal USS correcting the deviation from a predetermined USS. This study assessed USS differences between chronic pancreatitis (CP), early CP (ECP), and normal pancreas when using endoscopic ultrasound (EUS). The usefulness of measuring optimal USS was evaluated for patients with CP, including early stage patients. METHODS: This study enrolled 116 consecutive patients for whom USS was measured using an EUS system. The USS correction principle is generation of a B-mode image by changing the USS in all ranges while correcting the delay in the received data. Final diagnoses were made according to the Japanese diagnostic criteria for CP in 2019. They were classified as CP, ECP, or normal. We compared USS applied for these three groups. RESULTS: The medians and ranges of USS values for patients in the normal, ECP, and CP groups were 1506.0 (1407-1600) m/s, 1580.0 (1520-1630) m/s, and 1574.0 (1537-1610) m/s, respectively. The USS values of the ECP and CP groups were significantly higher than those of the normal group (P < 0.001). Analyses of the receiver operating characteristic curve in the normal pancreas, ECP, and CP revealed the area as 0.957, with specificity and sensitivity of 95.9% and 87.5%, respectively, using the USS of 1535 m/s as a cut-off. CONCLUSION: Measurement of USS might be particularly useful for distinguishing between normal and ECP imaging.


Assuntos
Pancreatite Crônica , Endossonografia , Humanos , Pancreatite Crônica/diagnóstico por imagem , Curva ROC , Ultrassonografia
10.
J Clin Med ; 10(16)2021 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-34442035

RESUMO

Ultrasonographic elastography is a modality used to visualize the elastic properties of tissues. Technological advances in ultrasound equipment have supported the evaluation of elastography (EG) in endosonography (EUS). Currently, the usefulness of not only EUS-strain elastography (EUS-SE) but also EUS-shear wave elastography (EUS-SWE) has been reported. We reviewed the literature on the usefulness of EUS-EG for various diseases such as chronic pancreatitis, pancreatic solid lesion, autoimmune pancreatitis, lymph node, and gastrointestinal and subepithelial lesions. The importance of this new diagnostic parameter, "tissue elasticity" in clinical practice might be applied not only to the diagnosis of liver fibrosis but also to the elucidation of the pathogeneses of various gastrointestinal diseases, including pancreatic diseases, and to the evaluation of therapeutic effects. The most important feature of EUS-EG is that it is a non-invasive modality. This is an advantage not found in EUS-guided fine needle aspiration (EUS-FNA), which has made remarkable progress in the field of diagnostics in recent years. Further development of artificial intelligence (AI) is expected to improve the diagnostic performance of EUS-EG. Future research on EUS-EG is anticipated.

11.
Diagnostics (Basel) ; 11(3)2021 Mar 03.
Artigo em Inglês | MEDLINE | ID: mdl-33802623

RESUMO

In 2009, diagnostic criteria for early chronic pancreatitis (DCECP2009) were proposed by the Japan Pancreas Society. This study aimed to evaluate the interobserver reliability (IOR) of endoscopic ultrasound (EUS) criteria for diagnosis of early chronic pancreatitis (ECP) between DCECP2009 and 2019 diagnostic criteria for ECP (DCECP2019) to assess the validity of the revision from the perspective of EUS findings. Among patients who underwent a detailed observation of the pancreas by EUS at our institution between January 2018 and March 2019, EUS images of 97 patients were extracted. Images were reviewed by 12 gastrointestinal endoscopy experts (eight pancreatologists, group A and four nonpancreatologists, group B). The overall kappa (K)-values for the IOR of the DCECP2009 EUS criteria were 0.424 and 0.563:0.231 for groups A:B, whereas the overall K-values for the DCECP2019 criteria were 0.618, and 0.733:0.442 for groups A:B. Regarding changes in the final diagnosis of ECP based on clinical features and EUS findings, 20 cases were definite ECP, 53 were probable ECP, and 24 were normal according to DCECP2009. In contrast, seven were definite ECP, 19 were probable ECP, and 71 were normal according to DECEP2019. IOR of DCECP2019 was higher than that of DCECP2009, which indicates an improvement in precision.

12.
J Clin Med ; 10(5)2021 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-33800779

RESUMO

Success rates of balloon enteroscopy-assisted endoscopic retrograde cholangiopancreatography (BE-ERCP) for patients with a reconstructed intestinal tract after surgical procedures are unsatisfactory. We retrospectively investigated the factors associated with unsuccessful BE-ERCP. Ninety-one patients who had a reconstructed intestinal tract after gastrectomy or choledochojejunostomy were enrolled. Age, sex, operative method, malignancy, endoscope type, endoscopist's skill, emergency procedure, and time required to reach the papilla/anastomosis were examined. The primary endpoints were the factors associated with unsuccessful BE-ERCP selective cannulation, while the secondary endpoints were the rate of reaching the papilla/anastomosis, causes of failure to reach the papilla/anastomosis, cannulation success rate, procedure success rate, and rate of adverse events. Younger age (odds ratio, 0.832; 95% CI, 0.706-0.982; p = 0.001) and Roux-en-Y partial gastrectomy (odds ratio, 54.9; 95% CI, 1.09-2763; p = 0.045) were associated with unsuccessful BE- ERCP. The rate of reaching the papilla/anastomosis was 92.3%, the success rate of biliary duct cannulation was 90.5%, procedure success rate was 78.0%, and the rate of adverse events was 5.6%. In conclusion, Roux-en-Y partial gastrectomy and younger age were associated with unsuccessful BE-ERCP. If BE-ERCP is extremely difficult to perform in such patients after Roux-en-Y partial gastrectomy, alternative procedures should be considered early.

13.
Biomed Mater Eng ; 32(2): 63-71, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33720871

RESUMO

BACKGROUND: Endoscopic transpapillary stenting is commonly performed in patients with obstructive jaundice caused by a biliary stricture. Although the plastic stent (PS) is widely used for biliary drainage because of the low-cost and easy procedure, patency is short after placement in the bile duct because of the small diameter. Dysfunction of PS is primarily caused by biliary sludge that forms as a result of bacterial adhesion and subsequent biofilm formation on the inner surface of the stent. It is well known that silver ions have excellent antibacterial activity against a wide range of microorganisms. OBJECTIVE: This review provides an overview and perspective of the significance of silver-coated biliary stents. METHODS: We collected literature regarding silver-coated biliary stents, reviewed the current research/development status and discussed their possible usefulness. RESULTS: To date, several in vivo/vitro studies evaluated the patency of silver-blended or silver-coated biliary stents. These studies suggested that the silver coating on a PS was likely to prolong the patency period. CONCLUSION: The development of biliary stents using silver is expected to prolong stent patency and prevent frequent stent replacement.


Assuntos
Prata , Antibacterianos , Colestase , Drenagem , Humanos , Stents , Resultado do Tratamento
14.
Diagnostics (Basel) ; 10(12)2020 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-33255736

RESUMO

Esophageal varices are caused by the development of collateral circulation in the esophagus as a result of portal hypertension. It is important to administer appropriate preventive treatment because bleeding varices can be fatal. Esophageal varices have complex and diverse hemodynamics, and there are various variations for each case. Endoscopic ultrasound (EUS) can estimate the hemodynamics of each case. Therefore, observation by EUS in esophageal varices provides useful information, such as safe and effective treatment selection, prediction of recurrence, and appropriate follow-up after treatment. Although treatment for the esophagogastric varices can be performed without EUS imaging, understanding the local hemodynamics of the varices using EUS prior to treatment will lead to more safe and effective treatment. EUS observation is an indispensable tool for thorough variceal care.

15.
Diagnostics (Basel) ; 10(11)2020 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-33203069

RESUMO

Endoscopic ultrasonography (EUS) has been applied to the diagnosis of various digestive disorders. Although it has been widely accepted and its diagnostic value is high, the dependence of EUS diagnosis on image interpretation done by the endosonographer has persisted as an important difficulty. Consequently, high interobserver reliability (IOR) in EUS diagnosis is important to demonstrate the reliability of EUS diagnosis. We reviewed the literature on the IOR of EUS diagnosis for various diseases such as chronic pancreatitis, pancreatic solid/cystic mass, lymphadenopathy, and gastrointestinal and subepithelial lesions. The IOR of EUS diagnosis differs depending on the disease; moreover, EUS findings with high IOR and those with IOR that was not necessarily high were used as diagnostic criteria. Therefore, to further increase the value of EUS diagnosis, EUS diagnostic criteria with high diagnostic characteristics based on EUS findings with high IOR must be established.

16.
Medicine (Baltimore) ; 96(50): e8937, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29390283

RESUMO

RATIONALE: There is currently no consensus on the ideal method for obtaining deep tissue biopsy material of advanced gastric LP. EUS-FNA has potential as a useful diagnostic method. Thus, we report the case of a 46-year-old male with advanced gastric linitis plastica (LP) who was diagnosed using endoscopic ultrasound-guided fine needle aspiration (EUS-FNA). PATIENT CONCERNS: The patient underwent esophagogastroduodenoscopy (EGD) because of epigastric pain at a local clinic. The gastric fold swelling was pointed out by the EGD and despite the suspected advanced gastric LP, biopsy indicated Group 1. Repeat biopsy did not suggest malignancy. The patient was referred to our institution. DIAGNOSES: Endoscopic ultrasound indicated gastric wall thickening mainly in the greater curvature of the gastric corpus. Low-level echoes were detected throughout the entire gastric wall, and gastric wall layers had been disappeared. EUS-FNA of the gastric wall indicated signet ring cell carcinoma. INTERVENTIONS: As a result of EUS - FNA, it became a policy to administer chemotherapy. In accordance with the patient's wishes, he was referred to another institution for chemotherapy. OUTCOMES: Normal biopsy did not give a definitive pathological diagnosis, and final diagnosis of LP was obtained with EUS-FNA. LESSONS: We expect that EUS-FNA can be utilized as a relatively non-invasive, highly sensitive, and specific pathological diagnostic procedure for advanced gastric LP. EUS-FNA should be considered as one way to obtain a deep tissue biopsy of advanced gastric LP.


Assuntos
Aspiração por Agulha Fina Guiada por Ultrassom Endoscópico , Linite Plástica/diagnóstico , Neoplasias Gástricas/diagnóstico , Diagnóstico por Imagem , Humanos , Linite Plástica/patologia , Masculino , Pessoa de Meia-Idade , Neoplasias Gástricas/patologia
17.
J Am Chem Soc ; 129(51): 15752-3, 2007 Dec 26.
Artigo em Inglês | MEDLINE | ID: mdl-18052281

RESUMO

6,13-Dipropyl-5,14-dihydropentacene was aromatized by the combination of the formation of pentacene-DDQ adduct and abstraction of DDQ from the pentacene-DDQ adduct with 50 equiv of gamma-terpinene to give 6,13-dipropylpentacene cleanly. It was stable and isolable. In the presence of a catalytic amount of acid, 6,13-dipropylpentacene was isomerized to its tautomer.

18.
Anal Sci ; 23(10): 1249-51, 2007 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-17928677

RESUMO

Measurements of time of flight (TOF) mobility of organic semiconductors become difficult when the mobility values are high, since the electronic signals overlap with the noise of the short part in drift time. Such noise of the short part in the drift time in the TOF method for measurements of carrier mobility was reduced by three methods: (1) longer distance (3.5 m) between sample and the N(2) laser, (2) optical connection (photo coupler) between the N(2) laser and the pulse generator, and (3) using a digital filter to remove characteristic pulses caused by N(2) laser. Each method showed significant reduction of the noise. When all three methods were applied, 94% of the noise was reduced. The measurement of TOF mobility was demonstrated with TPD (N,N'-diphenyl-N,N'-di(meta-tolyl)benzidine) film. Electronic signals in TOF measurements were clearly observed and the TOF mobility was determined to be 9.0 x 10(-4) cm(2)/V s.

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